1. Field of the Invention
The present invention relates, generally, to a vehicle body and, more particularly, to an extending and retracting device for a step of the vehicle body.
2. Description of the Related Art
With improvement of living standards, there are increased demands for comfortability of vehicles, such as cars. The step under a door of a vehicle is the only way to get on or off the vehicle. However, it is difficult to meet the trafficability and convenience requirements simultaneously when mounting the vehicle step. Considering trafficability of the vehicle, the level of the vehicle step should be higher than the ground clearance of the vehicle. In terms of ergonomics, the vehicle step is generally mounted at a level of 15 cm with respect to the ground so that it is convenient for a passenger of the vehicle to get on or off it, but this level cannot meet the trafficability requirements of most vehicles.
In view of this problem, retractable vehicle-step devices for use with automotive vehicles have been developed in the related art. The extending and retracting device of such known retractable vehicle-step devices typically employs a four-link mechanism. When the vehicle door is opened, the vehicle step is automatically extended out downwardly from the chassis of the vehicle near the board of the body of the vehicle so that a passenger can step on the extended vehicle step. When the vehicle door is closed, the vehicle step is automatically retracted upwardly to its original position, thus not affecting disadvantageously the trafficability of the vehicle.
Chinese Patent Application CN1652955, the description of which is incorporated herein by reference, also discloses such a retractable vehicle-step apparatus that employs an extending and retracting device in the form of a four-link mechanism. However, this extending and retracting device suffers from at least two disadvantages. First, the distance between two pivot shafts connecting the four-link mechanism and the vehicle step is short so that stress tends to concentrate on the pivot shafts' position when a passenger steps on the extended vehicle step. Thus, the pivot shafts tend to be destroyed over time due to their lack of mechanical strength. Therefore, reliability is reduced, and cost is increased. Second, the retractable vehicle-step apparatus employs a buffering structure in the form of a stopping block, thus increasing the complexity of the apparatus.
Thus, there is a need in the related art for an extending and retracting device for a vehicle step having increased reliability and reduced cost and complexity. More specifically, there is a need in the related art for a vehicle-step device in which stress is distributed evenly and that includes a buffering structure that is mechanically simple and cost-effective to manufacture.